Diethyl squarate → 6-chloro-3-(2-ethoxy-3,4-dioxo-cyclobut-1-enylamino)-2-hydroxy-N-methoxy-N-methyl-benzenesulfonamide

Participants

Reaction Conditions

Reaction Steps

A solution of 3,4-diethoxy-3-cyclobutene-1,2-dione (2.83 g, 1.2 equiv) in ethanol (30 ml) was treated with TEA (1.54 g, 1.1 equiv) and the reaction mixture was heated to 45° C. 3-Amino-6-chloro-2-hydroxy-N-methoxy-N-methyl-benzenesulfonamide (3.7 g, 1 equiv) was added portion wise over 30 minutes, with vigorous stirring, maintaining the reaction mixture at 45′C. The reaction mixture was stirred at 45° C. for 1 hour and then allowed to cool to RT. The solvent was removed in vacuo and the residue was partitioned between EtOAc (600 ml) and water (2×200 ml). The aqueous portion was separated and extracted with EtOAc (3×200 ml) and the combined organic extracts were washed with water (3×200 ml) and allowed to stand over night. The resulting solid was collected by filtration and dried in vacuo to afford the title compound. The mother liquor was evaporated to give a yellow/brown oily solid which was triturated with ethanol (100 ml). The solid was collected by filtration, washed with EtOH and dried in vacuo to afford the title compound; [M+H]+ 390.

Provenance & Evidence